"in one http request there are multiple connections, thats why we need to use oneconnect."
It is the other way around, multiple HTTP requests in the same connection.
Here is the solution you were talking about in relation to cookie persistence:
https://support.f5.com/csp/article/K7964
As described in the solution, one option is to use oneconnect and another option is to use LB::detach.
The oneconnect provides 2 important functions, first make sure every HTTP request triggers a new load balance decision.
Second, reuse the server side connection.
Persistence, on the other hand, is to make sure there is no new load balancing decision when you come back, so you go to the same server.
Based on what you said, I guess oneconnect with cookie persistence looks to be a good option for your case.